Method for preparing fibers of polyethylene-1,2-diphenoxyethane-4,4{40 -dicarboxylate

ABSTRACT

Stretched synthetic fibers are prepared by spinning polyethylene-1,2-diphenoxyethane-4,4&#39;&#39;-dicarboxylate which has been obtained by copolymerizing comonomer(s) containing one or more metal salts of strong acid having a pKa value of 3.5 or less and has the residual carboxyl groups in the polymer of 20 gramequivalents or less per 106 g at a high winding speed of 1,500 to 5,000 m/min, and continuously or discontinuously 5 to 50 percent stretching the thus obtained fibers. The stretched fibers have a good strength, a good boiling water shrinkage and a good bending and wearing strength. The textile plain-woven from the stretched fibers has a good wrinkling resistance. This invention relates to a method for high speed spinning, and more particularly to a method for preparing fibers of polyethylene-1,2-diphenoxyethane-4,4&#39;&#39;-dicarboxylate containing a high speed spinning step, characterized by using a copolymer of polyethylene-1,2-diphenoxyethane-4,4&#39;&#39;-dicarboxylate. According to the conventional method for preparing fibers by melt spinning, a polymer is melted, and extruded through nozzles; the thus obtained filamentary products are once wound up; said unstretched filaments having a low strength, a low degree of crystallization and a low degree of orientation are led to a stretching and twisting step to effect the stretching; the orientation and crystallization are also effected thereby; and thus fibers sufficiently durable as yarns are obtained. That is, good physical properties as good yarns are endowed only by passing the materials through the two steps such as spinning step and the stretching-and-twisting step. The conventional method is obviously not preferable from the economical point of view as well as in view of various properties of yarns, for example, uniformity, because it requires the discontinuous two steps. In order to overcome the above-mentioned disadvantage, several attempts have been made to endow various physical properties required as fibers to yarns by eliminating stretching step and effecting orientation and crystallization in a spinning step where material is extruded through nozzles, solidified and wound up. For example, a high speed winding of the filaments high speed winding of the filaments extruded through nozzles at 3,000-5,200 yd/minute or more has been proposed, as seen in Japanese Patent Publications Nos. 3104/60 and 6768/56. However, the thread prepared by the conventional direct spinning method based on such high speed winding has actually had a relative high residual percentage stretching, a low yield point strength and particularly a poor stretching recovery. Other disadvantage is a devitrification. That is, it has been very difficult to endow sufficient physical properties and transpaRency to the yarns obtained by the direct spinning method. An object of the present invention is to provide a method for preparing fibers of polyethylene-1,2-diphenoxyethane-4,4&#39;&#39;dicarboxylate by direct spinning method based on the high speed winding, quite free of said various disadvantages. As a result of a wide range of researches on homopolymers or copolymers of polyester or polyamide in connection to the direct spinning method, the present inventors have found polyethylene1,2-diphenoxyethane-4,4&#39;&#39;-dicarboxylate as a polymer composition suitable for the direct spinning method, which is prepared by copolymerizing a comonomer or comonomers containing one or more metal salts of strong acid having a pKa value of 3.5 or less, and have established the method of the present invention. The present method is to prepare fibers having a good transparency and good physical properties by effecting a high speed winding at 1,500 m to 5,000 m/minute, using polyethylene1,2-diphenoxyethane-4,4&#39;&#39;-dicarboxylate prepared by copolymerizing a comonomer or comonomers containing one or more metal salts of strong acid having pKa of 3.5 or less and having residual carboxyl group in the polymer of 20 gram-equivalents/106 g polymer or less in effecting the direct spinning, and effecting a 5 to 50 percent stretching of the thus obtained fibers of the said polymer having a birebriengence of 0.010 to 0.25. The amount of residual carboxyl group, as referred to above is determined according to a method of H.A. Pohl, Anal. Chem. 26 1614 (1954) using benzyl alcohol as a solvent, chloroform as a dispersing liquid and phenol red as an indicator, where the titration is effected with caustic soda in a benzyl alcohol solvent. When the amount of residual carboxyl group in the polymer exceeds 20 gram-equivalents/106 g, a decrease in the yield point strength is observed. The reduced viscosity of the polymer is preferably 0.5-1.5. When it is less than 0.5, the strength is reduced, and only insufficient physical properties as yarns are thereby endowed. On the contrary, when the reduced viscosity exceeds 1.5, the spinnability is lowered, and the filaments are often broken at the spinning. Thus, the reduced viscosity of over 1.5 is not preferable. The reduced viscosity, as referred to above, is a viscosity of a polymer having a polymer concentration of 0.5g/100cc of a solvent mixture of tetrachloethane and phenol at a mixing ratio of the former to the latter of 2:1 by weight, determined at 35*C. The metal salt of strong acid, as referred to above, is a comonomer or comonomers containing sulfinate group, sulfonate group, phosphonate group, etc. in the form of metal salt. Examples of these monomers include, as the phosphonates, disodium 3,5-dicarbomethoxybenzenephosphonate, sodium 4carbomethoxyphenyl-4&#39;&#39;-tolylphosphonate, disodium gamma carbomethoxypropanephosphonate; as the sulfinates, sodium pcarboxy-1,2-diphenoxyethane-p&#39;&#39;-sulfinate, sodium 3,5dicarbomethoxybenzenesulfinate, sodium p-carboxy-1,2diphenoxyethane-p&#39;&#39;-sulfinate, sodium 0-( Beta carbomethoxyethyl)benzenesulfinate; as the sulfonate, disodium p, p&#39;&#39;-dicarbomethoxy-1,2-diphenoxyethane-m,m&#39;&#39;-disulfonate, sodium pcarboxy-1,2-diphenoxyethane-p&#39;&#39;-sulfonate, sodium m,m&#39;&#39;dicarbomethoxy-1,2-diphenoxyethane-p&#39;&#39;-sulfonate, sodium mcarbomethoxy-1,2-diphenoxyethane-p&#39;&#39;-sulfonate, sodium p-( Beta gamma -epoxypropoxy) benzenesulfonate, etc., but are not limited thereto. More important factor of these monomers is a compatibility between these polar monomers and a polymerization reaction system. In general, these metal salts have a low compatibility and accordingly their copolymerizabilities become lower. Thus, the phase separation is inevitable and in the case of very insoluble comonomer, the filaments inevitably tend to have a white turbidity. In view of these facts, a monomer having such a unit structure as is preferable. In copolymerizing these comonomers, the addition of the comonomers may be effected in any step prior to the condensation polymerization reaction of polyethylene-1,2-diphenoxyethane-4,4&#39;&#39;dicarboxylate. That is, the comonomers can be added during, before or after the esterification reaction of 1,2-bis(p-carboxyphenoxy) ethane and ethyleneglycol, or during, before or after the ester interchange reaction of 1,2-bis(p-carbomethoxyphenoxy) ethane with ethyleneglycol. The amount of monomers used in the copolymerization is 0.1-10 percent by mole, preferably 5 percent by mole or less on the basis of 1,2-bis(p-carboxyphenoxy)ethane or 1,2-bis(pcarbomethoxy phenoxy)ethane. In the case of less than 0.1 percent by mole, such effect can hardly be obtained. On the other hand, in the case of more than 10 percent by mole, a decrease in spinnability is observed. The spinning result of using a copolymer of polyethylene-1,2diphenoxyethane-4,4&#39;&#39;-dicarboxylate having a reduced viscosity of 0.8 is given in Table 1. The comonomer used is sodium-p,p&#39;&#39;carbomethoxy-1,2-diphenoxyethane-m-sulfonate. The copolymer is melted at 285*C and extruded through nozzles of 0.5 mm, and their spinnability is investigated with respect to the maximum winding speed, filament breakage and winding speed which brings about devitrification, and its result is listed in Table 1.

United States Patent Kobayashi et al.

[151 3,689,623 1451 Sept. 5, 1972 [54] METHOD FOR PREPARING FIBERS OF POLYETHYLENE-l,2- QIPHENOXYETHANE-4A- DICARBOXYLATE [72] Inventors: Hidehiko Kobayashi, Tokyo;

Kiichiro Oimachi Sasaguri, lrumagun; Kazuya Neki; Noboru Tanimura, both of Tokyo, all of Japan [73] Assignee: Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan [22] Filed: Dec. 17,1969

21 Appl. No.: 885,703

[52] US. Cl ..264/210 F, 260/47 C, 264/290 [51] Int. Cl. ..D01d 5/12 [58] Field of Search ..260/75 S, 75 P, 75 R, 40 C,

260/47 C; 264/210 F, 290 F, 176 F WRINKLING RESISTANCE 3,406,224 10/ 1968 McDonough ..260/75 P 3,432,590 3/1969 Papps ..264/168 3,475,381 10/1969 Price ..260/75 3,489,722 1/1970 Kotani et a1. ..260/75 P 3,513,110 5/1970 Noethe ..260/2.5

FOREIGN PATENTS OR APPLICATIONS 1,046,069 10/ 1966 Great Britain ..260/47 C 1,047,978 1 1/1966 Great Britain ..264/290 T Primary Examiner-Jay H. Woo Attorney-Fred C. Philpitt {5 7] ABSTRACT Stretched synthetic fibers are prepared by spinning polyethylene- 1 ,2-diphenoxyethane-4,4 '-dicarboxylate which has been obtained by copolymerizing comonomer(s) containing one or more metal salts of strong acid having a pKa value of 3.5 or less and has the residual carboxyl groups in the polymer of 20 gramequivalents or less per 10 g at a high winding speed of 1,500 to 5,000 m/min, and continuously or discontinuously 5 to 50 percent stretching the thus obtained fibers. The stretched fibers have a good strength, a good boiling water shrinkage and a good bending and wearing strength.

The textile plain-woven from the stretched fibers has a good wrinkling resistance.

8 Claims, 1 Drawing Figure STRETCHI NG RATIO 1%) PNENTEDSEP 5191 2 2'0 3'0 STRETCHING RATIO IOO- METHOD FOR PREPARING FIBERS 0F POLYETHYLENE- l ,2-DIPHENOXYETHANE-4,4 DICARBOXYLATE This invention relates to a method for high speed spinning, and more particularly to a method for preparing fibers of polyethylene-l ,2-diphenoxyethane-4,4'- dicarboxylate containing a high speed spinning step, characterized by using a copolymer of polyethylenel ,2-diphenoxyethane-4,4 -dicarboxylate.

According to the conventional method for preparing fibers by melt spinning, a polymer is melted, and extruded through nozzles; the thus obtained filamentary products are once wound up; said unstretched filaments having a low strength, a low degree of crystallization and a low degree of orientation are led to a stretching and twisting step to effect the stretching; the orientation and crystallization are also effected thereby; and thus fibers sufficiently durable as yarns are obtained. That is, good physical properties as good yarns are endowed only by passing the materials through the two steps such as spinning step and the stretching-and-nvisting step. The conventional method is obviously not preferable from the economical point of view as well as in view of various properties of yarns, for example, uniformity, because it requires the discontinuous two steps.

In order to overcome the above-mentioned disadvantage, several attempts have been made to endow various physical properties required as fibers to yarns by eliminating stretching step and effecting orientation and crystallization in a spinning step where material is extruded through nozzles, solidified and wound up. For example, a high speed winding of the filaments high speed winding of the filaments extruded through nozzles at 3,0005,200 yd/minute or more has been proposed, as seen in Japanese Patent Publications Nos. 3104/60 and 6768/56.

However, the thread prepared by the conventional direct spinning method based on such high speed winding has actually had a relative high residual percentage stretching, a low yield point strength and particularly a poor stretching recovery. Other disadvantage is a devitrification. That is, it has been very difiicult to endow sufficient physical properties and transparency to the yarns obtained by the direct spinning method.

An object of the present invention is to provide a method for preparing fibers of polyethylene-1,2- diphenoxyethane-4,4'-dicarboxylate by direct spinning method based on the high speed winding, quite free of said various disadvantages.

As a result, of a wide range of researches on homopolymers or copolymers of polyester or polyamide in connection to the direct spinning method, the present inventors have found polyethylene-1,2- diphenoxyethane-4,4'-dicarboxylate as a polymer composition suitable for the direct spinning method, which is prepared by copolymerizing a comonomer or comonomers containing one or more metal salts of strong acid having a pKa value of 3.5 or less, and have established the method of the present invention.

The present method is to prepare fibers having a good transparency and good physical properties by effecting a high speed winding at 1,500 m to 5,000 m/minute, using polyethylene-l,2-diphenoxyethane- 4,4'-dicarboxylate prepared by copolymerizing a comonomer or comonomers containingone or more metal salts of strong acid having pKa of 3.5 or less and having residual carboxyl group in the polymer of 20 gram-equivalents/ 10 g polymer or less in effecting the direct spinning, and effecting a 5 to 50 percent stretching of the thus obtained fibers of the said polymer having a birebriengence of 0.0 l 0 to 0.25.

The amount of residual carboxyl group, as referred to above is determined according to a method of HA. Pohl, Anal. Chem. 26 l6l4 (1954) using benzyl alcohol as a solvent, chloroform as a-dispersing liquid and phenol red as an indicator, where the titration is ef fected with caustic soda in a benzyl alcohol solvent. When the amount of residual carboxyl group in the polymer exceeds 20 gram-equivalents/ l 0 g, a decrease in the yield point strength is observed.

The reduced viscosity of the polymer is preferably 0.5-l.5. When it is less than 0.5, the strength is reduced, and only insufficient physical properties as yarns are thereby endowed. On the contrary, when the reduced viscosity exceeds 1.5, the spinnability is lowered, and the filaments are often broken at the spinning. Thus, the reduced viscosity of over 1.5 is not preferable. The reduced viscosity, as referred to above, is a viscosity of a polymer having a polymer concentration of 0.5g/l00cc of a solvent mixture of tetrachloethane and phenol at a mixing ratio of the former to the latter of 2:1 by weight, determined at 35C.

The metal salt of strong acid, as referred to above, is a comonomer or comonomers containing sulfinate group, sulfonate group, phosphonate group, etc. in the form of metal salt. Examples of these monomers include, as the phosphonates, disodium 3,5dicarbomethoxybenzenephosphonate, sodium 4-carbomethoxyphenyl-4-tolylphosphonate, disodium ycarbomethoxypropanephosphonate; as the sulfinates, sodium p-carboxy-l ,2-diphenoxyethane-p'-sulfinate, sodium 3,5-dicarbomethoxybenzenesulfinate, sodium p-carboxy-l ,2-diphenoxyethane-p-sulfinate, sodium 0- (B-carbomethoxyethyl)benzenesulfinate; as the sulfonate, disodium p,p-dicarbomethoxy-l,Z-diphenoxyethane-m,m'-disulfonate, sodium p-carboxy-l,2- diphenoxyethane-p-sulfonate, sodium m,m-dicarbomethoxyl ,2-diphenoxyethane-p'-sulfonate, sodium m-carbomethoxy-l ,Z-diphenoxyethane-p '-sulfonate, sodium p-(B-y-epoxypropoxy) benzenesulfonate, etc., but are not limited thereto. More important factor of these monomers is a compatibility between these polar monomers and a polymerization reaction system. In general, these metal salts have a low compatibility and accordingly their copolymerizabilities become lower. Thus, the phase separation is inevitable and in the case of very insoluble comonomer, the filaments inevitably tend to have a white turbidity. In view of these facts, a monomer having such a unit structure as is preferable.

In copolymerizing these comonomers, the addition of the comonomers may be effected in any step prior to the condensation polymerization reaction of polyethylene-l ,2-diphenoxyethane-4,4'-dicarboxylate. That is, the comonomers can be added during, before or after the esterification reaction of l,2-bis[p-carboxy-phenoxy] ethane and ethyleneglycol, or during, before or after the ester interchange reaction of 1,2-bis[pcarbomethoxyphenoxy] ethane with ethyleneglycol.

The amount of monomers used in the copolymerization is 0.1-10 percent by mole, preferably 5 percent by mole or less on the basis of 1,2-bis[p-carboxyphenoxy] ethane or 1,2-bis[p-carbomethoxy phenoxy]ethane. In the case of less than 0.1 percent by mole, such effect can hardly be obtained. On the other hand, in the case of more than percent by mole, a decrease in spinnability is observed.

TABLE 1 Filament breakage Winding speed Amount of Maximum (occurences which brings comonomer winding [8 hours) about devitri copolymerised speed m/min. (winding at fication by mole) 2000 m/min.) (m/min.)

- 5,000 or more 2,500 or more 4,500 or more 5,000 or more 4,000 or more 2,500 or more 1,200 or more 4,000 or more 2,500 3,000 1,500 2,000

As is clear from the Table, no effect of copolymerized comonomer upon the transparency is observed almost at all, if it is in an amount of 0.1 percent by mole or less. On the other hand, when the comonomer is copolymerized in an amount of 10 percent by mole or more, the spinnability, particularly filament breakage, becomes considerable and the maximum winding speed is lowered.

Further considerable effect is dyeability by a cationic dyestuff. It is a very surprising fact that fibers of polyethylene-1 ,2-diphenoxyethane-4,4 -dicarboxylate show no dyeability by a cationic dyestuff almost at all, even if said acidic groups are introduced thereinto. Such properties are shown as ordinary yarns in Table 2. On the other hand, the yarns prepared according to the present invention have a considerable improvement in dyeability, as seen from the Table. The improvement in the dyeability according to the present method is different from the conventional modification by copolymerization, and is regarded as a very excellent method for endowing dyeability by a basic dyestuff in that the melting point or the physical properties are not deteriorated, and has a great advantage.

TABLE 2 S OaNu Percentage dyestuff adsorption The dyeing is effected under following conditions: 3% owf of Astrazon Blue as a dyestuff; bath ratio; l/50; acetic acid, 1 ml/1;l00 C;90 minutes, and the percentage dyestuff adsorption is determined.

* The directly wound-up yarns are prepared under following conditions: spinning temperature of 285C; spinning nozzle diameter of 0.5 mm da; linear extrusion speed of 3.4 m/min; winding speed of 3000 m/min; stretching by 1.2 times is carried out at a stretching temperature of C to give 2 denier yarns.

*" The ordinary yarns are prepared by effecting spinning at a spinning temperature of 285C, winding up at a speed of 1500 m/min. and then stretching by 4 times at 140C to give 2 denier yarns.

In carrying out the present invention, the yarns spun and wound up at 1,500 to 5,000 m/min. are 5 to 50 percent stretched. One of the important disadvantages of the textile woven from the conventional high speed wound-up yarns is a poor wrinkling resistance. As a result of strenuous research of a method for overcoming such disadvantage, the present invention has been accomplished.

The stretched yarns can be wound up after the stretching has been effected continuously through several rollers and hot plates inserted between the nozzles and the winding rollers, or the once wound yarns can be further stretched discontinuously.

In said range of the stretching conditions, there are mutual relations among birefringence, percentage stretching of unstretched yarns and the obtained effect upon improvement in the wrinkling resistance. With the untreated yarns having a smaller birefringence, an effect can be obtained at higher percentage stretching. However, when the firefringence is less that 0.10, the effect upon improvement in the wrinkling resistance is small, even if the stretching is effected. Such relations are shown in FIG. 1.

FIG. 1 is a graph showing an effect of the percentage stretching of unstretched fibers having different double refractions upon the wrinkling resistance.

In Figure, the curve A shows the case where the birefringence n 0.05, likewise the curve B shows the stretching effect in the case of n 0.10, the curve C in the case of n =0.15, the curve D in the case of n =0.20 and the curve E in the case of n 0.25. On the other hand, when the birefringence of the unstretched yarns is increased, the stretching effect can be obtained at such a low stretching zone of 5 to 10 percent.

However, when the birefringence is further increased, the stretching becomes difficult and the effect of stretching upon the improvement in the wrinkling resistance is lowered.

The wrinkling resistance, as referred to above, is a ratio to 180 of an angle of a textile piece of fibers of polyethylene-1 ,2-diphenoxyethane-4,4 '-dicarboxylate polymer, the angle being formed when the piece is folded and placed upon a flat table, a load of 500 g is placed upon the folded piece and left for 5 minutes and then the piece is placed on a knife edge and left for 5 minutes.

. yethane-4,4-dicarboxylate Further interesting effect is an improvement in flexing abrasion resistance. The textile obtained from the yarns prepared according to the present method has a good flexing abrasion resistance. Such properties are shown in Table 3, where the strength and the boiling water shrinkage are listed. It is seen from the Table that the strength and the boiling water shrinkage are not changed almost at all. The textile used is a plain-woven textile of 75d/36f yarns at a warp density of 99 warps per inch and a weft density of 88 wefts per inch and is used for test after scouring and heat setting. The flexing abrasion resistance is determined according to Universal method, using a pressing load of one-fourth pound and a tensile load of one-half pound.

TABLE 3 Flexing abrasion It is further noted that the influence of stretching temperature is small and said restretching effect can be obtained in a range of 175C to room temperature. When it exceeds 175C, the flexing abrasion resistance is lowered. On the other hand, a sufficient effect can be obtained by using either dry heating or humid heating as a stretching medium.

Though the present invention relates to a method for spinning a copolymer of polyethylene-1,2-diphenoxwith strongly acidic comonomer, the present invention can be also applied to a copolymer containing at least one of other additional monomers. That is, in addition to the strongly acidic comonomer, a small amount of copolymerizable monomer, that is, at least one of the members selected from other glycols, dicarboxylic acids, their lower alkylesters or oxycarboxylic acids, may be added during the preparation of said polyester ether. Thus, the polymer consisting substantially of polyethylene-1,2- diphenoxyethane-4,4-dicarboxylate may contain up to percent by mold of other glycols such as diethylene glycol, tetramethylene glycol, or hexamethylene glycol in the polymer molecule in addition to the strongly acidic copolymerizable monomer. Further, it may contain likewise up to 10 percent by mole of other acids. As suitable examples of copolymerizable acids are illustrated hexahydroterephthalic acid, terephthalic acid, isophthalic acid, bibenzoic acid, adipic acid, sebacic acid, azelaic acid, naphthalic acid, 2,5-dimethylterephthalic acid, their lower alkyl esters, etc.

The advantages obtained according to the present method are further explained hereunder in detail, referring to Examples:

v EXAMPLE 1 l,2-bis(p-carbomethoxyphenoxy) ethane (0.98 mole) and disodium-p,p -dicarbomethoxy-1 ,2- diphenoxyethane-m,m'-disulfonate (0.02 mole) were subjected to esterinterchange with ethylene glycol (2.50 mole) at 200C for 3 hours, by using 0.04 percent by weight of manganese acetate as a catalyst and then polymerized at 280C under a reduced pressure of 0.1 mm Hg, by using 0.02 percent by weight of germanium dioxide as a polymerization catalyst.

Thus obtained polyethylene-l,Z-diphenoxyethanep,p'-dicarboxylate (reduced viscosity: 0.75, melting point: 246C, amount of residual carboxyl groups in the polymer: l6 gram-equivalent/ 10 g) was melted at a spinning temperature of 290C and extruded through nozzles of 0.5 mm and spun at the first and second roller speeds of 2,400 m/min., a hot plate temperature of 140C and a winding roller speed of 3,000 m/min., whereby yarns of 2 denier were obtained.

The yarns had a tensile strength of 4.1 g/d, a tensile elongation of 25 percent, and an initial modulus of elasticity of 131 g/d, had a good transparency and luster and showed a percentage adsorption of 52 percent by Astrazon Blue BC.

The plain-woven textile fabrics from said yarns at a warp density of 99 warps per inch and a weft density of 85 wefts per inch was tested to determine the wrinkling resistance and the flexing abrasion resistance, and the wrinkling resistance of and the flexing abrasion resistance of 2,600 flexions were obtained.

COMPARATIVE EXAMPLE 1 Homopolymer of polyethylene-1 ,2-diphenoxy-4,4 dicarboxylate (reduced viscosity: 0.75, melting point: 249C, and amount of residual carboxyl group in the polymer: 16 gram-equivalent/ 1 0 g) was spun under the same conditions as in Example 1, in place of the copolymer. The thus obtained yarns had a tensile strength of 3.3 g/d, a tensile elongation of 44 percent and an initial modulus of elasticity of 104 g/d. but were devitrified and had a poor yarn luster. The percentage adsorption by Astrazon Blue BG was almost zero.

EXAMPLE 2 Polyethylene-l,2-diphenoxyethane-4,4-dicarboxylate copolymerized with 2 per cent by mole of the monomer listed in Table 4 as copolymerizable monomer as described in Example 1 (reduced viscosity: 0.75, and amount of residual carboxyl group in the polymer: 12 to 17 gram-equivalent/ 10 g) was spun in the same manner as in Example 1, and the transparency and percentage adsorption of the yarns were determined.

EXAMPLE 3 0.98 moles of 1,2-bis[p-carboxyphenoxy] ethane, and 0.02 moles of sodium-mm'-dicarboxy-1,2- diphenoxyethane-p'-sulfonate, were esterfied with 2.5 moles of ethylene glycol at 240C. and then polymerized at 280C under a pressure of 0.1 mm Hg by using 0.015 percent by weight of germanium dioxide as a catalyst.

Thus obtained polyethylene-1,2-diphenoxy-4,4- dicarboxylate copolymer, (reduced viscosity: 0.80, melting point: 245C) was melted at 285C, spun through nozzles of 0.5 mm 1: and wound up. The thus obtained yarns were further stretched by 1.25 times by a stretching machine and the influences of the amount of residual carboxyl group in the polymer upon the mechanical properties of the thus obtained yarns were investigated.

TABLE As shown in Table 5, the yield point strength tends to be lowered when the amount of residual carboxyl group in the molecule exceeds 20 gramequivalent/ g.

EXAMPLE 4 Polyethylene-1 ,2-diphenoxyethane-4,4 '-dicarboxylate copolymerized with 2 percent by mole of sodium pcarboxy-l,Z-diphenoxyethane-p'-sulfonate and 5 percent by mole of diethylene glycol (reduced viscosity: 0.83, melting point: 242C, and the amount of residual carboxyl groups in the polymer: gramequivalent/10 g) was melted at 285C and passed through the nozzles of 0.5 mm 4). The thus obtained yarns were wound up under the conditions as shown in Table 6, and then passed through steam at 100C to stretch by 1.2 times. Various physical properties of the thus obtained stretched yarns are investigated and the result is shown in Table 6.

TABLE 6 The yarns wound up at 3,500 m/min. in Example 4 were stretched in steam at 100C, and the dyeability and the wrinkling resistance of the thus obtained yarns are investigated, and the result is shown in Table 7.

LII

TABLE 7 Percentage wrinkling Percentage 1 stretching(%) resistance(%) dyestuff adsorption(%) 3.0 45 '60 5.0 52 60 10.0 61 57 30.0 69 55 50.0 55 52 70.0 41 41 100.0 40 33 Unstretched 39 61 yarn What is claimed is:

l. A method for preparing fibers which comprises: a. spinning a copolymer of polyethylene 1,2-

diphenoxyethane-4,4-dicarboxy1ate which 1. has been obtained by copolymerizing polyethylene-1 ,2-diphenoxyethane-4-4-dicarboxylate with 01-10 mol percent of at least-one comonomer selected from the group consisting of disodium 3,5-dicarbomethoxybenzenephosphonate, sodium 4-carbomethoxyphenyl-4-tolylphosphonate, disodium y-carbomethoxypropanephosphonate; sodium p-carboxy-1 ,2-diphenoxyethane-p'-su1finate, sodium 3,5-dicarbomethoxybenzenesulfinate, sodium pcarboxy-l ,2-diphenoxyethane-p-sulfinate, sodium O-(B-carbomethoxyethyl)benzenesulfinate; disodium p,p'-dicarbomethoxy-1 ,2-diphenoxyethane-m,m'm'-disulfonate, sodium p-carboxy- 1 ,2-diphenoxyethanep'-sulfonate, sodium m,m-dicarbomethoxy-1 ,2-diphenoxyethane-psulfonate, sodium m-carbomethoxy-l ,2- diphenoxyethane-p-sulfonate, and sodium p- (fi-y-epoxypropoxy )benzenesulfonate, 2. has residual carboxyl groups in the copolymer in an amount of 20 gram equivalents or less per 10 g. of the copolymer, and 3. has a reduced viscosity of 0.5 to 1.5, b. said spinning being carried out at a high winding speed of 1,500 to 5,000 m/min., and c. stretching the thus obtained fibers by 5 to 50 percent at a temperature ranging from room temperature to C. 2. A method for preparing fibers which comprises: a. spinning a copolymer of polyethylene-1,2-

diphenoxyethane-4,4-dicarboxylate which 1. has been obtained by copolymerizing polyethylene- 1 ,2-diphenoxyethane-4-4'-dicarboxylate with 01-10 mol percent of at least one comonomer containing at least one metal salt of strong acid having a pKa value of 3.5 or less, said acid salt being selected from the group consisting of sulfinate, sulfonate or phosphonate, 2. has residual carboxyl groups in the copolymer in an amount of 20 gram equivalents or less per 10 g. of the copolymer b. said spinning being carried out at a high winding speed of 1,500 to 5,000 m/min., and c. stretching the thus obtained fibers by 5 to 50 percent. 3. A method according to claim 2 wherein the polyethylene-1 ,2-diphenoxyethane-4,4 '-dicarboxylate copolymer has a reduced viscosity of 0.5 to 1.5.

' diphenoxyethane-p-sulfonate,

0 Q-O C H20 HQOQ and containing on the benzene ring, sulfinate, sulfonate or phosphonate group in the form of metal salt.

6. A method according to claim 2 wherein the stretching is effected at a temperature ranging from a room temperature to C.

7. A method according to claim 2 wherein said copolymer contains at least one other monomer selected from the group consisting of glycols, dicarboxylic acids, lower alkylesters of dicarboxylic acids, and oxycarboxylic acids.

8. A method according to claim 7 wherein up to 10 mo] percent of said other monomer is present. 

2. A method for preparing fibers which comprises: a. spinning a copolymer of polyethylene-1,2-diphenoxyethane-4, 4''-dicarboxylate which
 2. has residual carboxyl groups in the copolymer in an amount of 20 gram equivalents or less per 106 g. of the copolymer b. said spinning being carried out at a high winding speed of 1, 500 to 5,000 m/min., and c. stretching the thus obtained fibers by 5 to 50 percent.
 2. has residual carboxyl groups in the copolymer in an amount of 20 gram equivalents or less per 106 g. of the copolymer, and
 3. has a reduced viscosity of 0.5 to 1.5, b. said spinning being carried out at a high winding speed of 1, 500 to 5,000 m/min., and c. stretching the thus obtained fibers by 5 to 50 percent at a temperature ranging from room temperature to 175*C.
 3. A method according to claim 2 wherein the polyethylene-1,2-diphenoxyethane-4,4''-dicarboxylate copolymer has a reduced viscosity of 0.5 to 1.5.
 4. A method according to claim 2 wherein said comonomers are selected from the group consisting of disodium 3,5-dicarbomethoxybenzenephosphonate, sodium 4-carbomethoxy-phenyl-4''-tolylphosphonate, disodium gamma -carbomethoxypropane-phosphonate; sodium p-carboxy-1,2-diphenoxyethane-p'' -sulfinate, sodium 3,5-dicarbomethoxybenzenesulfinate, sodium p-carboxy-1,2-diphenoxyethane-p'' -sulfinate, sodium 0-( Beta -carbomethoxyethyl)benzenesulfinate; disodium p,p''-dicarbomethoxy-1,2-diphenoxyethane-m,m''-disulfonate, sodium p-carboxy-1,2-diphenoxyethane-p''-sulfonate, sodium m,m''-dicarbomethoxy-1,2-diphenoxyethane-p''-sulfonate, sodium m-carbomethoxy-1,2-diphenoxyethane-p''-sulfonate, and sodium p-( Beta - gamma -epoxypropoxy) benzenesulfonate.
 5. A method according to claim 2 wherein said comonomer is selected from the group consisting of the compounds having a unit of and containing on the benzene ring, sulfinate, sulfonate or phosphonate group in the form of metal salt.
 6. A method according to claim 2 wherein the stretching is effected at a temperature ranging from a room temperature to 175*C.
 7. A method according to claim 2 wherein said copolymer contains at least one other monomer selected from the group consisting of glycols, dicarboxylic acids, lower alkylesters of dicarboxylic acids, and oxycarboxylic acids.
 8. A method according to claim 7 wherein up to 10 mol percent of said other monomer is present. 